CC2652RB: Can the LED module in syscfg achieve a duty cycle adjustable waveform

Cherry Zhou

Part Number: CC2652RB

Hi team,

Here's an issue from the customer may need your help:

The customer would like to implement "1 Hz, on 200 ms, off 800 ms, and flicker 10 times", but due to the below restrictions, it failed:

The LTE module enables blinking of the LED as well as brightness control.
The period value of the PWM cannot be set too large (the LED does not work when greater than some value), is there any limitation? Setting pwmPeriod to 1000 works fine, but the LED does not light up when set to 1000000.

Could you help check this case? Thanks.

Best Regards,

Cherry

over 3 years ago

+1 daniel_o over 3 years ago

TI__Genius 10610 points

Cherry,

For PWM mode, you can not set a period larger than ~350ms. This because the PWM timer is 24-bit wide running at 48 MHz. You can read more about the PWM driver here: https://dev.ti.com/tirex/explore/content/simplelink_cc13xx_cc26xx_sdk_5_30_01_01/docs/drivers/doxygen/html/_p_w_m_timer_c_c26_x_x_8h.html

Regards,

Daniel

+1 Ryan Brown1 over 3 years ago

TI__Guru**** 217617 points

Hi Cherry,

Basically, the period counts (48000000 for a 48 MHz clock and 1 second period) are above the allowed PWM_COUNT_MAX range (24-bit or 0xFFFFFF) which causes the PWM TI Driver (and thus the LED TI Driver) to fail. Thus the customer will need to generate their own solution using the Timer TI Driver API, they can start with the timerled example.

Regards,
Ryan

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CC2652RB: Can the LED module in syscfg achieve a duty cycle adjustable waveform